Sound-reproducing stylus.



J. C. MERCER.

SOUND REPRODUCING STYLUS.

APPLICATION FILED DEC 6. 1915.

Fin?

INVENTOR Ldvqttlrwha Patented Apr. 3, 1917.

JOHN c. amncnn, or PITTSBURGH, PENNSYLVANIA.

SOUND-REPRODUCING STYLUS.

mamas.

specification of Letters Patent.

Patented Apr. 3, fair.

Application filed December 6, 1915. Serial No. 65,282.

To all whom it may concern."

Be it known that I, JOHN C. MERCER, a citizen of the United States of America, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have in vented new and useful Improvements in Sound-Reproducing Styli, of which the following is a full, clear, and exact description, reference being had to the accompanying drawing, forming part of this specification.

This invention is a new and improved needle or stylus by means of which sounds are reproduced from the record of a phonograph or similar sound reproducing machine. It has been customar to make this needle from steel and from her or similar substances, and it is a well known fact that the use of a steel needle is not only injurious to the delicate records but it produces harsh metallic tonesand is unable to effectively transmit the lesser and more delicately sustained tones, while the fiber needle or the like, results in such softness of tone as to make it unsuitable for general use. Furthermore, the fiber needle is objectionable on account of the ready wear or breaking down of its operative point.

The object of my invention is to'provide a needle which shall not be injurious to the record, which shall reproduce at a moderate tone and which is therefore comprehensive of a large number or range of records, which shall have the maximum wearing qualities, and which can be made at a very low cost.

To the above end, I make a needle of bone which is preferably treated, as hereinafter set forth, for the purpose of building up the qualities aforesaid. k

I will now describemy invention so that others skilled in the art to which it appertains may understand and construct the same, it being apparent that so far as the shape of the needle is concerned, changes may be made without departing from the invention as herein claimed.

Figure 1 is an enlarged elevational view of a reproducing head or sound transmitting box of a phonograph, having applied thereto a needle embodying my lnvention, and Figs. 2, 3 and 4 indicate in elevation groups of needles constructed 1n accordance with my invention and all to be hereinafter more fully described.

To prepare the bone for the formation of theyneedle I preferably first subject it to a thorough steaming or boiling to remove a greater part of the nitrogenous or organic matter. I next apply heat to the bone sufiic iently to refine its texture through contract on and elongation of the canals and cavit es thereof. Removal of the greater pormen of the nitrogenous constituent and refinement of the bone results in a character of material of great density of structure but which is not too brittle and which effectively resists at its operative point destruction due to vibratory impact on the face of the record and other wear. If desired, the bone before being made up into the needle, or the needle, may be given an additional harden.- ing treatment by subjecting it to the action of tannic acid. This effects a desirous surface or superficial hardening.

Although not limited to any particular shape, I find that I obtain striking results in the use of a needle of either of the shapes illustrated in Figs. 2, 3 and 4. "It will of course be understood that the needle is provided with a shank or body portion 2 by means of which it is held in the vise 3 of the reproducing head 4. In Fig. 2 the operative point of the needle is shown as formed by cutting away on an angle the fiat face 5 so as to orm a plane 6 which intersects the plane of the opposite fiat face 5 at an an le, producing an edge 7 in the plane of the side 5". With the needle placed in the holder or vise 3 of the sound reproducing head, this edge 7 lies disposed toward the face of the record; I

In Fig. 3the edge 7 is formed by uniformly beveling the face 5.

In Fig. 4 is shown a needle similar in shape to that of Fig. 2. However, the edge of the needle is cut away as at 9 to form a point and the face 5 is out way opposite the edge 9 in a plane intersecting the plane of the face 5, to form the operative edge 7.

It will of course be understood that I do not limit myself to any particular shape, and

it will also be apparent that modifications may be made in the method of treating the bone preparatory to forming the needle.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. A sound reproducing stylus of bone free from a part of its organlc constituent and having its operative point hardened.

2. A sound reproducing stylus formed of bone free from a part of its organic constituent and having an operative point of a density caused. by structural shrinkage and by hardening.

3. The method of making a sound repro- 5 ducing stylus from bone, which consists in dissolving the organic constituent of the bone, drying the bone to produce structural shrinkage, cutting the stylus from the bone and then hardenlng the operative point of the stylus.

In testimony whereof I have he sunto set my hand.

JOHN C. MERCER. 

